If symptoms such as headache or shortness of breath do not improve promptly with simple changes, visiting a doctor may be helpful if descent is inconvenient and a doctor is available.

Descend immediately if shortness of breath at rest, mental confusion or lethargy, or loss of muscle coordination develop. Symptoms of most people with AMS improve by the time they reach a medical facility, which is usually located at a lower altitude.

If descent is not possible, a portable hyperbaric chamber (Gamow bag) can be used to simulate a lower altitude.

The higher the altitude at which a hyperbaric chamber is used, the greater the apparent descent can be simulated. (This is because portable hyperbaric chambers can increase atmospheric pressure by 2 pounds per square inch.)

For example, a hyperbaric chamber at 9,800 feet (3,000 meters) can simulate a descent of 4,800 feet (1,500 meters), but the same hyperbaric chamber used at 24,600 feet (7,500 meters) can simulate a descent of 7,800 feet (2,400 meters).

Increase the sleeping altitude by no more than 1,000 feet (300 meters) per 24 hours. The mountaineer’s rule is "climb high, sleep low." This means that on layover days, a climber can ascend to a higher elevation during the day and return to a lower sleeping elevation at night. This helps to hasten acclimatization.

Outlook

The prognosis for acute mountain sickness is excellent as long as common sense is used. Descending, delaying further ascent, rest, and paying attention to the body’s symptoms are usually all that is necessary to ensure a complete recovery.

High altitude pulmonary edema (HAPE) has a good outcome if symptoms are recognized and treated early. If descent is impossible or if hyperbaric therapy, supplemental oxygen, and access to medical care are not available, HAPE can progress to respiratory failure and ultimately to death. Remember that HAPE is the number one cause of death from high altitude illness.

More than half of people with HACE who develop coma die. Of those who survive, mental impairment and coordination defects may continue to affect them. HACE can be fatal if not recognized and treated quickly.